1. Field of the Invention
Aspects of the present invention relate to a method of forming a thin film, and more particularly, to an evaporating method for forming a thin film, wherein various types of multi-layer films can be formed on an object to be processed.
2. Description of the Related Art
An organic thin film including an emission material layer in a flat-panel display device, such as an organic light emitting display (OLED) device, is typically formed using a thin-film evaporation process in which a material to form the organic thin film is evaporated in vacuum conditions.
Typically, only a single thin-film is obtained by performing the thin-film evaporation process once. Therefore, in the case of an OLED device, if it is desired to stack multiple layers in a composite structure, such as in an organic thin film including an emission material layer, the evaporation process is repeated multiple times according to the total number of the multiple layers. Therefore, a process of forming multiple layers may be time-consuming.
To resolve this problem, Japanese Patent Publication No. 2004-111305 discloses an evaporating method for forming an organic thin film, wherein two evaporating sources are sequentially moved toward the lower side of a target so that organic thin films are sequentially stacked. However, in this described method, deposition from one evaporation source is performed only after completing deposition from another evaporation source within one chamber. Therefore, although the described method provides an advantage that deposition is performed in one chamber, such that it is not necessary to move the target from a chamber, the method still requires two evaporating operations, and thus the total evaporation time used to form the organic thin film is not reduced. Also, if a film is a type that is formed by mixing two different evaporating source materials, such as a host material and a dopant material, residue gases from the evaporating source materials used in a first evaporating operation may remain within the chamber after the first evaporating operation is over. Thus, the evaporating source material for forming a film may be corrupted in the second evaporating operation due to the residue gases from the first evaporating operation. Therefore, the chamber has to be ventilated between the first and second evaporating operations.